> Support for XDebug exists in all modern editors - Atom, Sublime, NetBeans, etc. etc.
It does, but PHPStorm's is particularly competent. From rewinding the stack, having an in-context command line prompt to run code in, conditional debug points, current context auto-complete for the command line, it can even read cachegrind outputs. It's the level of competence they implement in all their features that take it from a "text editor preference" to a professional level tool.
> I must say PHPStorm had a superior look-for-file (think: Ctrl+P) feature
You can also "look everywhere" which looks at literally everything from the same text-box, so if I type "show line numbers" it searches through the settings panes and finds the "show line numbers" setting, and because it's a toggle, I can just hit enter on the search result and it toggles the setting. Also class definitions (PHP, Javscript and CSS definitions) are all fuzzy searchable. "SoClNa" will find the SomeClassName definition and also the "Some/Class/Name" folder and so on.
I know I'm gushing about it but I really could talk for ages about all the little things it does.